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Effectiveness of equipping bus stop shelters with cooling and filtering systems in a city with tropical climate

Erik Velasco (Molina Center for Energy and the Environment, Boston, Massachusetts, USA)
Elvagris Segovia (Department of Geography, National University of Singapore, Singapore, Singapore)

Smart and Sustainable Built Environment

ISSN: 2046-6099

Article publication date: 29 August 2023




Waiting for a bus may represent a period of intense exposure to traffic particles in hot and noisy conditions in the street. To lessen the particle load and tackle heat in bus stops a shelter was equipped with an electrostatic precipitator and a three-step adiabatic cooling system capable of dynamically adjust its operation according to actual conditions. This study evaluates the effectiveness of the Airbitat Oasis Smart Bus Stop, as the shelter was called, to provide clean and cool air.


The particle exposure experienced in this innovative shelter was contrasted with that in a conventional shelter located right next to it. Mass concentrations of fine particles and black carbon, and particle number concentration (as a proxy of ultrafine particles) were simultaneously measured in both shelters. Air temperature, relative humidity and noise level were also measured.


The new shelter did not perform as expected. It only slightly reduced the abundance of fine particles (−6.5%), but not of ultrafine particles and black carbon. Similarly, it reduced air temperature (−1 °C), but increased relative humidity (3%). Its operation did not generate additional noise.

Practical implications

The shelter's poor performance was presumably due to design flaws induced by a lack of knowledge on traffic particles and fluid dynamics in urban environments. This is an example where harnessing technology without understanding the problem to solve does not work.


It is uncommon to come across case studies like this one in which the performance and effectiveness of urban infrastructure can be assessed under real-life service settings.



The authors thank independent research scientist Armando Retama for his valuable comments.


Velasco, E. and Segovia, E. (2023), "Effectiveness of equipping bus stop shelters with cooling and filtering systems in a city with tropical climate", Smart and Sustainable Built Environment, Vol. ahead-of-print No. ahead-of-print.



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